Project Summary/Abstract The goal of this Ruth L. Kirschstein National Research Service Award is to support the applicant in developing the specialized skills necessary to build an independent program of research with the goal of improving the implementation of contextually relevant and culturally responsive evidence-based treatments (EBTs) in schools, and thereby promoting equitable mental health services for historically underserved youth. This F32 application proposes research to address NIMH strategic priority 4.1: Improve the efficiency and effectiveness of existing mental health services through research, specifically by contributing to the budding knowledgebase on the modifications made to EBTs in practice, and thereby optimizing the effective implementation of EBTs in real-world contexts. The research component of this F32 responds to a call to action by leaders of the NIH Implementation Science Team, who have advocated for the compilation of a comprehensive body of knowledge identifying the modifications that are made to EBTs in practice and explaining their impacts on relevant outcomes. The proposed research will be conducted in two stages: Study 1 will develop a novel coding scheme that integrates theoretical models from implementation science and cultural adaptation, using modified Delphi procedures with an expert panel comprised of implementation science researchers and cultural adaptation researchers (Research Aim 1). Using this coding scheme, Study 2 will examine the modifications made to an EBT being implemented within schools, through the use of mixed quantitative and qualitative methods. Specifically, data will be collected from school-based mental health providers via quantitative measures and semi-structured interviews, and the coding scheme developed in Study 1 will be used to identify which modifications are being made to an EBT as it is implemented in schools, and why they are being made (Research Aim 2). Finally, a set of hypotheses will be tested in order to estimate the construct validity of the coding scheme developed in Study 1 by examining expected associations between types of EBT modifications and clinician- and school-level variables (Research Aim 3). In combination, these two studies will provide a strong foundation for a Career Development Award focused on the impact of EBT modifications on child/adolescent mental health outcomes. In addition, by designing and engaging in a three-year progression of targeted training activities, the applicant will develop expertise in school-based mental health research, while gaining critical knowledge and skills in implementation science, cultural adaptation, and mixed methods research. Specific training goals to be achieved are to: 1) Build expertise in contextually relevant intervention research, with a particular emphasis on school-based mental health research; 2) Expand conceptual knowledge of the modifications made to EBTs in practice settings by integrating two pertinent, yet disparate, literatures?implementation science and cultural adaptation; 3) Develop experience and expertise in mixed methods research; and 4) Strengthen grant-writing and manuscript-writing skills.